1. Field of the Invention
This invention relates to a digital interpolation circuit. More particularly, this invention relates to a digital interpolation circuit for a digital-to-analog converter circuit.
2. Brief Description of the Related Technologies
Converting digital signals to analog signals is accomplished using a digital-to-analog converter (DAC). A DAC circuit may also include a digital interpolation circuit which is used to up-sample a multi-bit digital input signal so that the analog signal output from the DAC circuitry more closely approximates the analog signal that was originally digitized and which is now being converted back to analog form by the DAC circuit.
Existing digital interpolation circuits utilize circuits which are used to up-sample a given multi-bit digital input signal. As the number of coefficients for these circuits increases, in order to gain more precision, the complexity necessary for the interpolation circuits increases to the point where having a one-stage interpolation becomes unfeasible. As the number of coefficients increases, the number of taps on a one-stage interpolation filter also increases, so that for large numbers of coefficients a one-stage interpolation filter becomes very complex and expensive to manufacture.